The present invention integrates many elements of a Position Enhanced Cellular Telephone System (PECS) and user equipment (i.e., the vehicle applique unit VAU) into a single unit with improved performance characteristics and reduced unit cost. A VAU core includes GPS (or other broadcast) receiver circuitry for position location, a modem, a controller and an alarm interface. Additional cellular telephone interfaces for communicating via a cellular telephone channel are included.
The above referenced related applications disclose the position enhanced cellular telephone system (PECS). The objects of the present invention are to provide a PECS system, merge the cellular telephone and VAU core, accommodate both mobile and portable telephones, improve overall performance, and reduce and significantly lower unit cost.
Another object of the invention is to provide a system for enhancing the performance of a 0.6 Watt portable phone when used inside an automobile. This is achieved by use of a linear amplifier of appropriate gain and power level to compensate for RF losses, typically incurred by portables used in the automotive environment. Adjustments in power, as directed by the cellular network controller, are left to the portable telephone itself. The Integrated Unit, while described under the context of portable phones, is equally useful when applied as a part of a "mobile only" system.
Another object of the invention is provided by the architecture of the Integrated Unit which is transferable to forms of radio communication other than cellular telephone. For example, terrestrial/satellite based PCS, pagers, mobile radio and other emerging communication standards could be implemented with this architecture.
A further object of the invention is to provide additional RF switches inside the Integrated Unit for the purpose of selecting between dual cellular or GPS antennae.
A further object of the invention is to provide an integrated cellular transceiver VAU core which offers the following features: 1) voice-only operation, 2) data-in-voice operation, 3) data-only operation, 4) voice and message recording/playback, 5) interfaces to car alarms and vehicular data buses, and 6) enhanced portable phone performance.
Still a further object of the invention is to provide integrated cellular transceiver/VAU core units which can be used (without monthly billing) by leaving it in the "off" state until such time that a call is made to a service center. The call can be billed at a special roaming rate.